Method and system for assessing tennis stroke heaviness

Abstract

A method and system for assessing heaviness of a swing in sport of tennis is disclosed. The system may display the calculated heaviness of a groundstroke in real-time. As the player hits ground strokes, the system will measure linear and rotational speed of the ball and calculate a heaviness value based on the physics of translational and rotational kinetic energy of the ball.

The invention claimed is: 
     
       1. A system for assessing a tennis stroke, the system comprising:
 a sensor device containing one or more sensors capable of detecting parameters of movement of a tennis ball; 
 a processor; and 
 a memory containing programming instructions that are configured to, when executed, cause the processor to:
 receive, from the one or more sensors, the detected parameters of movement of the ball, 
 use the detected parameters to measure linear speed and rotational speed of the ball, 
 use the measurements of linear speed and rotational speed to generate a heaviness value for a stroke associated with the movement of the ball, and 
 output the heaviness value via a display or speaker. 
 
 
     
     
       2. The system of  claim 1 , wherein the instructions to use the measurements of linear speed and rotational speed to generate the heaviness value comprise instructions to use a function of a translational kinetic energy value and a rotational kinetic energy value of the ball. 
     
     
       3. The system of  claim 2 , wherein the instructions to use the function of translational kinetic energy and rotational kinetic energy of the ball comprise instructions to:
 adjust the translational kinetic energy value by a first weighting coefficient; 
 adjust the rotational kinetic energy energy value by a second weighting coefficient; and 
 sum the adjusted translational kinetic energy value and the adjusted rotational kinetic energy value. 
 
     
     
       4. The system of  claim 2 , wherein the instructions to generate the heaviness value comprise instructions to, in response to also receiving one or more characteristics of a court from which the sensor device collects data, include the one or more characteristics in the function. 
     
     
       5. The system of  claim 1 , wherein the instructions to measure linear speed of the ball comprise instructions to, when the one or more sensors comprise a camera:
 measure a distance that the ball has moved in a plurality of subsequent frames captured by the camera; and 
 use the measured distance and a frame rate of the camera to determine the linear speed of the ball. 
 
     
     
       6. The system of  claim 1 , wherein the one or more sensors comprise a camera, a radar system, a lidar system or an audio sensor. 
     
     
       7. The system of  claim 6 , wherein the one or more sensors are positioned to detect an area of a tennis court that begins on or before a baseline of the court and extends through and beyond a service line of the court. 
     
     
       8. The system of  claim 1 , wherein the one or more sensors comprise a receiver configured to receive signals transmitted by a sensor that is located in the ball. 
     
     
       9. The system of  claim 1  further comprising instructions to:
 use detected parameters of movement of an additional ball to generate an additional heaviness value for an additional stroke associated with the movement of the additional ball; 
 associate each ball's heaviness value with a time stamp indicating a time at which the parameters for that ball were captured; and 
 when outputting the heaviness values, use the time stamps of the heaviness values and time stamps of a video showing the strokes to synchronize the heaviness values with the strokes shown in the video. 
 
     
     
       10. A method of assessing a tennis stroke, the method comprising:
 by a sensor device, detecting parameters of movement of a tennis ball on a tennis court; 
 by a processor:
 receiving, from the one or more sensors, the parameters of movement of the ball, 
 using the detected parameters to measure linear speed and rotational speed of the ball, 
 using the measurements of linear speed and rotational speed to generate a heaviness value for a stroke associated with the movement of the ball, and 
 outputting the heaviness value via a display or speaker. 
 
 
     
     
       11. The method of  claim 10 , wherein using the measurements of linear speed and rotational speed to generate the heaviness value comprise using a function of a translational kinetic energy value and a rotational kinetic energy value of the ball. 
     
     
       12. The method of  claim 11 , wherein using the function of translational kinetic energy and rotational kinetic energy of the ball comprises:
 adjusting the translational kinetic energy value by a first weighting coefficient; 
 adjusting the rotational kinetic energy energy value by a second weighting coefficient; and 
 summing the adjusted translational kinetic energy value and the adjusted rotational kinetic energy value. 
 
     
     
       13. The method of  claim 11 , wherein generating the heaviness value comprises, in response to also receiving one or more characteristics of a court from which the sensor device collects data, including the one or more characteristics in the function. 
     
     
       14. The method of  claim 10 , wherein measuring linear speed of the ball comprises, when the one or more sensors comprise a camera:
 measuring a distance that the ball has moved in a plurality of subsequent frames captured by the camera; and 
 using the measured distance and a frame rate of the camera to determine the linear speed of the ball. 
 
     
     
       15. The method of  claim 10 , wherein the one or more sensors comprise a camera, a radar system, a lidar system or an audio sensor. 
     
     
       16. The method of  claim 10 , wherein detecting the parameters of movement of the tennis ball comprises detecting the parameters on an area of a tennis court that begins on or before a baseline of the court and extends through and beyond a service line of the court. 
     
     
       17. The method of  claim 10 , wherein:
 the one or more sensors are located in the ball; and 
 receiving, from the one or more sensors, the parameters of movement of the ball comprises receiving signals transmitted from the ball. 
 
     
     
       18. The method of  claim 10  further:
 using detected parameters of movement of an additional ball to generate an additional heaviness value for an additional stroke associated with the movement of the additional ball; 
 associating each ball's heaviness value with a time stamp indicating a time at which the parameters for that ball were captured; and 
 when outputting the heaviness values, using the time stamps of the heaviness values and time stamps of a video showing the strokes to synchronize the heaviness values with the strokes shown in the video. 
 
     
     
       19. A computer program product comprising a computer readable medium containing programming instructions that are configured to cause a processor to:
 receive, from the one or more sensors, parameters of movement of a tennis ball on a tennis court; 
 use the detected parameters to measure linear speed and rotational speed of the ball; 
 use the measurements of linear speed and rotational speed to generate a heaviness value for a stroke associated with the movement of the ball; and 
 output the heaviness value via a display or speaker.